Air conditioners for vehicles are installed to cool or heat the interior of vehicles during summer or winter or remove frost formed on wind shields when it rains or during the winter, and the like, to secure drivers' front or rear visual fields. Air-conditioners generally include both a heating system and a cooling system to selectively receive internal or external air, heat or cool the received air, and blow air to the inside of vehicles to cool or heat the inside or ventilate it.
A typical refrigerating cycle of such an air conditioner includes an evaporator for absorbing heat from the surroundings, a compressor for compressing a refrigerant, a condenser for releasing heat to the surroundings, and an expansion valve for expanding the refrigerant. In a cooling system, a gaseous refrigerant flowing to the compressor from the evaporator is compressed to have a high temperature and high pressure in the compressor, and when the compressed refrigerant in the gaseous state passes through the condenser and is liquefied, heat of liquefaction is released to the surroundings. The liquefied refrigerant passes through the expansion valve again to become low-temperature and low-pressure wet saturated steam, and then flows to the evaporator again and is vaporized to absorb the heat of vaporization from the surroundings to cool ambient air, thus cooling the inside of a vehicle.
The condenser, the evaporator, and the like, used in the cooling system are typical heat exchangers, and a lot of continuous research includes studies on effective heat exchange between ambient air of a heat exchanger and a heat exchange medium, i.e., a refrigerant, inside the heat exchanger. The most direct effect of indoor cooling is manifested by efficiency of evaporators, and thus, various structural research and development have been done and made to improve heat exchange efficiency of evaporators.
In order to enhance heat exchange efficiency of evaporators, an example having a dual-evaporation structure in which a core including tubes and fins are dually provided to form first and second rows as spaces in which a refrigerant flows therein has been proposed.
Conventionally, Japanese Patent Laid-Open Publication No. 2005-308384 (“Ejector Cycle”, Nov. 4, 2005) discloses a configuration similar to a dual-evaporator in which a refrigerant flows in each of a first row and a second row.
Here, in the dual-evaporator, a header tank arranged on an upper side or a lower side is divided into two rows by a partition and a communication hole may be provided in the partition, which partitions first and second rows each allowing a refrigerant to flow therein, in order to connect the first and second rows to configure a flow path for flowing of a refrigerant.
However, the header tank does not have a drain hole in a portion corresponding to an intermediate position between the first row and the second row, making it difficult for condensate generated in refrigerant tubes and fins configuring the evaporator to be drained through the header tank when heat is exchanged.
In order to form a drain hole to drain condensate in the header tank, a portion corresponding to an intermediate position between the first and second rows may be narrowed to form a drain hole, but with this structure, it is difficult to form a communication hole connecting the first row and the second row and structural strength is so weak to degrade durability.